The family of slain backpacker Grace Millane have called on the Government to reform our laws and ban the "rough sex" defence after the UK Parliament voted to outlaw the controversial legal tactic.

"We now hope that the rest of the world takes notice, and follows our lead, especially New Zealand. Changes need to be made to protect women," the family said in a statement.

MPs in the UK have backed an amendment to the Domestic Abuse Bill which rules out "consent for sexual gratification" as a defence for causing serious harm.

British Home Office minister Victoria Atkins told the Commons that the increased use of the defence was a "chilling and anguished" development.

"We've been clear that there is no such defence to serious harm which results from rough sex," Atkins said.

"But there is a perception that such a defence exists and that it is being used by men, and it is mostly men in these types of cases, to avoid convictions for serious offences or to receive a reduction in any sentence where they are convicted."

The murder of Grace Millane, who was killed while travelling through New Zealand in 2018, was one of several high-profile cases that spurred lawmakers to make the change.

Her killer, who cannot be identified for legal reasons, was sentenced to life imprisonment with a minimum non-parole period of 17 years after Millane was killed in an Auckland city apartment on the eve of her 22nd birthday after a Tinder date.

During the trial, family and friends heard details of Millane's sexual preferences — claims she was unable to challenge.

After sentencing, Auckland Crown Solicitor Brian Dickey said there was a high-level of cruelty, callousness and brutality in Grace's murder.

"Manual strangulation, the act which must have killed Miss Millane. It is a very close, personal and callous thing to do to another person.

"It was a violent death for Grace Millane."

Detective Inspector Scott Beard, the police officer who oversaw the investigation, said after the trial that the "rough sex" defence should not be used.

"If people are going to use that type of defence all it actually does is repeatedly re-victimises the victim and the victim's family. In this case the Millanes had to sit through a trial for a number of weeks and their daughter's background, rightly or wrongly, was out in the public," he said.

"I don't believe rough sex should be a defence, [but] I understand why the defence would use it."

Ahead of the UK law change, the Millane family spoke out to call for it to be adopted worldwide, singling New Zealand out.

In comments posted to Twitter by British Labour MP Harriet Harman, who spearheaded the UK campaign, Millane's family said: "We are pleased that the government are stopping 'Rough Sex' being used as a defence. It needs to be called what it really is and that's murder."

"Families won't have to sit & listen to only one side of the story whilst the victim is revictimised & doesn't get to tell their side," they added.

"It was truly horrendous listening to the defence, it felt like Grace was on trial, yet not able to defend herself.

"Hopefully this means no other family has to go through this & men will stop using this defence as an excuse to kill women, knowing they can get a lesser sentence.

"We now hope that the rest of the world takes notice, and follows our lead, especially New Zealand. Changes need to be made to protect women & make sure this doesn't happen again."